Hesperian Health Guides

Testing Range of Motion of Joints and Strength of Muscles

Every day 20,000 people visit the HealthWiki for lifesaving health information. A gift of just $5 helps make this possible!

Make a giftMake a gift to support this essential health information people depend on.

HealthWiki > Disabled Village Children > Chapter 4: Examining and Evaluating the Disabled Child > Testing Range of Motion of Joints and Strength of Muscles

Children who have disabilities that affect how they move often have some muscles that are weak or paralyzed. As a result, they often do not move parts of their bodies as much as is normal.

Loss of strength and active movement may in time lead to a stiffening of joints or shortening of muscles (contractures). As a result, the affected part can no longer be moved through its complete, normal range of motion.

Active movement

Normally the shoulder muscles can raise the arm until it is straight up. When the shoulder muscles are paralyzed, the child can no longer actively lift his arm.
a child holding his arm straight up.
Range of active motion
shoulder muscles used to raise arm
a child who can lift his arm only a few inches.
shoulder muscles small and weak
Reduced range of active motion
Lifting the arm like this with the arm’s own muscles is called ACTIVE MOTION.

Passive movement

At first the paralyzed arm can be lifted straight up with help. This is called PASSIVE MOTION. Unless the normal range of motion is kept through daily exercises, the passive range of motion will steadily become less and less.
a hand holding a child's wrist to lift the arm straight up.
Range of passive motion
a hand lifting a child's arm about half-way up.
tight cords and skin
Reduced range of passive motion
Now the arm cannot be raised straight up, even with help.

In the physical examination of a child with any weakness or paralysis of muscles, or joint pain, or scarring from injuries or burns, it is a good idea to test and record both RANGE OF MOTION and MUSCLE STRENGTH of all parts of the body that might have contractures or be affected. There are 2 reasons for this:

  • Knowing which parts of the body have contractures or are weak, and how much, can help us to understand why a child moves or limps as she does. This helps us to decide what activities, exercises, braces, or other measures may be useful.
  • Keeping accurate records of changes in muscle strength and range of motion can help tell us if certain problems are getting better or worse. Regular testing therefore helps us evaluate how well exercises, braces, casts, or other measures are working, and whether the child’s condition is improving, and how quickly.

For testing range of motion and muscle strength, it helps to first know what is normal. You can practice testing non-disabled, active persons. They should be of the same ages as the disabled children you will test. Age matters because babies are usually weaker and have much more flexible joints than older children. For example:

DVC Ch4 Page 27-5.png DVC Ch4 Page 27-6.png DVC Ch4 Page 27-7.png DVC Ch4 Page 27-8.png
A baby’s back and hips bend so much he can lie across his straight legs. A young child bends less but can usually touch his toes with his legs straight. Around 11 to 14 it is harder to touch toes. His legs grow faster and become longer than his upper body. Later, upper body growth catches up with legs. He can again touch toes more easily.

In different children (and sometimes in the same child) you may need to check range of motion and strength in the hips, knees, ankles, feet, toes, shoulders, elbows, wrists, hands, fingers, back, shoulder blades, neck, and jaw. Some joints have 6 or more movements to test: bending, straightening, opening, closing, twisting in, and twisting out. See, for example, the different hip movements (range-of-motion exercises) in Chapter 42.

To test both ‘range of motion’ and ‘strength’, first check ‘range of motion’. Then you will know that when a child cannot straighten a joint, it is not just because of weakness.

Range-of-motion testing: Example:


1. Ask the child to straighten it as much as she can.
a woman talks to a girl lifting her leg while sitting on a table.
Raise your foot and touch my finger.
Good girl!
a girl lying down while hands straighten her leg.
With your hands, support the joint on each side as you straighten it.

2. If she cannot straighten it all the way, gently see how far you can straighten it without forcing.

DVC Ch4 Page 28-3.png
If it still does not straighten, the range of motion is reduced. This is usually because of a contracture.

If it gradually straightens, spasticity (muscle spasms) may be what makes it difficult. (If it stops before it straightens completely, contractures may also be developing.)

3. If at first the joint will not straighten, keep trying with gentle continuous pressure for 2 or 3 minutes.

4. If a joint will not straighten completely, try with the child in different positions.

a boy sitting on a table.
For example, a knee often does not straighten as much with the hips bent as with the hips straight.
a boy lies down on a table and talks
Now it straightens more.
For this reason, each time you test range of motion to measure changes, be sure the child is in the same position.

Position affects how much certain joints straighten or bend. This is true in any child, but especially in a child with spasticity.

a girl tries to bend her knee and talks
That's all it will bend.
If joints are kept straight and never bent, they may stiffen or develop contractures that do not let them bend. (This can happen with joint infection, arthritis, and other conditions, or when a joint is kept in a cast for a long time.)

5. In addition to checking how much a joint straightens, check how much it bends.

6. Also check for too much range of motion.
a girl with her knee locked backward; a boy using crutches with his arms locked backward.
A child who walks on a weak leg often ‘locks’ her knee backward to keep from falling. In time, the knee stretches back more and more, like this.
The same thing can happen to the child with weak arms who uses crutches (or crawls).

Usually the best positions for checking range of motion are the same as those for doing range-of-motion and stretching exercises. These are shown in Chapter 42.

For methods of measuring and recording range of motion, see Chapter 5.

Precautions when testing for contractures

Testing range of motion of the ankles, knees, and hips is important for evaluating many disabled children. We have already discussed knees. Here are a few precautions when testing for contractures of ankles and hips.


DVC Ch4 Page 29-1.png
normal upward bend
DVC Ch4 Page 29-2.png
Test the range of motion with the knee as straight as it will go.
Feel the tight heel cord here.
DVC Ch4 Page 29-3.png
With the knee bent, the foot will usually bend up more. But for walking, we need to know how far it bends with the knee straight.
DVC Ch4 Page 29-7.png
Feel the tight cord here.
If the knee will not straighten, test him with his leg over the edge of a table.


To check how far the hip joint straightens, have the child hold his other knee to his chest, like this, so that his lower back is flat against the table. If his thigh will not lower to the table without the back lifting, he has a bent-hip contracture.

a child with his leg straight out
CAUTION! The hips will often straighten more at an angle to the body. So be sure to lower the leg in a straight line with the body, or you can miss contractures that need to be corrected before the child can walk.

Muscle testing

Muscle strength can be anywhere between normal and zero. Test it like this:

If the child can lift the weight of leg all the way, press down on it, to check if she can hold up as much weight as is normal for a girl her age. If she can, her strength is NORMAL.
a girl sitting on the edge of a table with her leg out straight.
NORMAL strength
If she can hold some extra weight, but not as much as is normal, she rates GOOD.
DVC Ch4 Page 30-2.png
Press down lightly.
GOOD strength
If she can just hold up the weight of her leg, but no added weight, she rates FAIR.
DVC Ch4 Page 30-3.png
FAIR strength
If she cannot hold up the weight of her leg, have her lie on her side and try to straighten it. If she can, she rates POOR.
DVC Ch4 Page 30-4.png
POOR strength
If she cannot straighten her knee at all, put your hand over the muscles as she tries to straighten it. If you can feel her muscles tighten, rate her TRACE.
someone tells a child to straighten her leg
Muscles move, but not leg:
TRACE strength
No muscle movement:
ZERO strength
Try as hard as you can to straighten your leg.

Test the strength of all muscles that might be affected. Here are some of the muscle tests that are most useful for figuring out the difficulties and needs of different children.

Note: These tests are simple and mostly test the strength of groups of muscles. Physical therapists know ways to test for strength of individual muscles.

Ankle and Foot

ankle and foot muscle tests
DVC Ch4 Page 30-7.png
If the child can walk, see if she can stand and walk on her heels and her toes.
a child walking on her toes and then on her heels.
NORMAL calf muscle
NORMAL foot-lift muscle
If he lifts his foot with his toes bent up, like this, see if he can lift it with his toes bent down, like this.
DVC Ch4 Page 30-9.png

Also notice if the foot tips or pulls more to one side. This may show ‘muscle imbalance’.

Note: Sometimes when the muscles that normally lift the feet are weak, the child uses his toe-lifting muscles to lift his foot.

To learn about which muscles move body parts in different ways, as you test muscle strength, feel which muscles and cords tighten.


knee muscle tests
You can feel the muscle tighten on top of the thigh.
Feel the muscles tighten on the back of the thigh.
Feel the tight cords pull here.


illustration of the above: hip muscle tests
DVC Ch4 Page 31-5.png
DVC Ch4 Page 31-6.png
DVC Ch4 Page 31-7.png

BENDING Feel the butt muscles tighten. If the hip has contractures, test with legs off end of table.
child lies up on a table and bends knee up
child lies down on a table and lifts knee up
child lies down on a table and lifts knee up with legs off end of table
Feel the side-of-hip muscles tighten here.
child lies on side and raises leg

Note: Weak hip muscles sometimes lead to dislocation of the hip. Be sure to check for this, too.

Testing side-of-hip muscles is important for evaluating why a child limps or whether a hip-band may be needed on a long-leg brace.

Stomach and Back

To find out how strong the stomach muscles are, see if the child can do ‘sit ups’ (or at least raise his head and chest). To test the back muscles, see if he can bend backward like this.
Sitting up with knees bent uses (and tests) mainly the stomach muscles. Feel stomach muscles tighten. Sitting up with knees straight uses the hipbending muscles and stomach muscles. Feel the muscles tighten on either side of the backbone. Notice if they look and feel the same or if one side seems stronger.
DVC Ch4 Page 32-1.png
DVC Ch4 Page 32-2.png
a child lying on his stomach with back bent and head raised.

hands hold child's hips as he moves around

You can check a child’s trunk control and strength of stomach, back, and side muscles like this. Have him hold his body upright over his hips, then lean forward and back, and side to side, and twist his body.

DVC Ch4 Page 32-5.png

If a child’s stomach and back muscles are weak, he may need braces with a body support—or a wheelchair.

IMPORTANT! Be sure to check for curvature of the spine— especially in children with muscle imbalance or weakness of the trunk.

Shoulders, Arms, and Hands

When a child’s legs are severely paralyzed but she has FAIR or better trunk strength, she may be able to walk with crutches if her shoulders, arms, and hands are strong enough.

Therefore, an important test is this:
a girl sitting on a table, pushing down with her hands to lift herself up.
Can she lift her butt off the seat like this?
If she can, she has a good chance for walking with crutches.

If she cannot lift herself, check the strength in her shoulders and arms:


arm muscle tests
Muscles tighten here.
Muscles tighten here.


shoulder muscle tests
Push down
Lift up
Push forward
Push back
Lift up
children using different crutches with elbow support
like this
elbow support
or like this

If the shoulder pushes down strongly but her elbow-straightening muscles are weak, she may be able to use a crutch with an elbow support.

DVC Ch4 Page 32-10.png

Or, if her elbow range of motion is normal, she may learn to ‘lock’ her elbow back like this. However, this can lead to elbow problems.

You may want to make a chart something like this and hang it in your examining area, as a reminder.

Evaluating Strength or Weakness of Muscles

CAUTION! To avoid misleading results, check range of motion BEFORE testing muscle strength.
Strength rating Test with the child positioned so that he lifts the weight of the limb.
DVC Ch4 Page 33-1-a.png
lifts and holds against strong resistance
DVC Ch4 Page 33-1.png
lifts and holds against some resistance
DVC Ch4 Page 33-2.png
lifts own weight but no more
DVC Ch4 Page 33-3.png

Test with the child positioned so that he can move the limb without lifting its weight (by lying on his side).
DVC Ch4 Page 33-1-b.png
cannot lift own weight but moves well without any weight.
DVC Ch4 Page 33-4.png
barely moves
DVC Ch4 Page 33-5.png
no sign of movement
DVC Ch4 Page 33-6.png

In muscle testing, it is especially important to note the difference between FAIR and POOR.

This is because FAIR is often strong enough to be fairly useful (for standing, walking, or lifting arm to eat). POOR is usually too weak to be of much use.

Sometimes with exercise POOR muscles can be strengthened to FAIR; this can greatly increase their usefulness. It is much less common for a TRACE muscle to increase to a useful strength (FAIR), no matter how much it is exercised. (However, if muscle weakness is due to lack of use, as in severe arthritis, rather than to paralysis, a POOR muscle can sometimes be strengthened with exercise to GOOD or even NORMAL. Also, in very early stages of recovery from polio or other causes of weakness, POOR or TRACE strength sometimes returns to FAIR or better.)

Other things to check in a physical examination

Difference in leg length.
When one leg is weaker, it usually grows slower, and becomes shorter than the other leg. An extra thick sole on the sandal might help the child stand straighter, limp less, and avoid curving of the spine. A short leg may also be a sign of a dislocated hip. So it helps to check for, and to measure, difference in leg length. (See about tests.)
DVC Ch4 Page 34-1.png
If the child can stand,
look for a tilt of the hip bones,

then raise the foot of the short leg until the hips are level
and measure the difference.

If she cannot stand,
have her lie as straight as she can. Feel and then mark, on both sides of her body, the bony lumps
at the top front corner of the hip bone
and on the inner ankle.
measuring difference in child's leg length
Then measure from here to here with a tape measure or string. Measure each leg and record the difference. If you used a string, just draw lines on your record sheet showing the actual difference in leg length.
Pass tape along inner side of knee.
Loli's difference in leg length (lying down)

June 3, 1986 |---|
Sept. 10, 1986 |-----|
Dec. 2, 1986 |-------|

Curve of the spine Especially when one leg is shorter or there are signs of muscle imbalance in the stomach or back, be sure to check for abnormal curve of the spine (back bone). The 3 main types of spinal curve (which may occur separately or in combination) are:

Sideways curve (scoliosis)
DVC Ch4 Page 34-3.png
shoulder higher on side of short leg
Check for weaker muscles on this side of spine.
Have the child bend over. Check for a rib hump on outer side of curve.
Hunch back,
rounded back
Swayback (lordosis)
May result from weak back muscles, or poor posture.
DVC Ch4 Page 34-4.png
DVC Ch4 Page 34-5.png
May result from weak stomach muscles or bent-hip contractures. (Be sure to check for these.)
a normal spine
Normal position of spine showing the 3 main divisions of the backbone.
Cervical (neck)
Thoracic (upper back)
Lumbar (lower back)

Some spinal curves will straighten when a child changes her position, lies down, or bends over. Other spinal curves will not straighten, and these are usually more serious. For more information about examining spinal curve and deformities of the back, see Chapter 20.

This page was updated:21 Nov 2019